Abstract: Disclosed are novel polypeptides of a four helix bundle formed of two dimerized helix-loop-helix motifs, wherein either both have a sequence according to SEQ. ID No. 1, SEQ. ID No. 2, SEQ. ID No. 3, SEQ. ID No. 4, SEQ. ID No. 5, or SEQ. ID No. 7, or one has a sequence according to SEQ. ID No. 6, and the other one has a sequence according to SEQ. ID No. 1, SEQ. ID No. 2, SEQ. ID No. 3, SEQ. ID No. 4, SEQ. ID No. 5 or SEQ. ID No. 7.

Abstract: A catalytically active peptide comprising an imidazole function in position i flanked by at least one functional group to be amidated in position i+3+4k, where k is an integer equal to or higher than ?1 or in position i?4?4n, wherein n is an integer equal to or higher than 0, characterized in that it also comprises at least one activating group in position i+4+4n or i?3?4n, respectively, wherein n is as above.

Abstract: Novel peptide having a sequence according to SEQ. ID. No. 1, SEQ. ID. No. 2 and/or SEQ. ID. No. 3 are disclosed and also polypeptide scaffold consisting of a four helix bundle formed of two dimerized helix-loop-helix motifs, said helix-loop-helix motifs having sequences according to SEQ. ID. No. 1, SEQ. ID. No. 2 and/or SEQ. ID. No. 3 which may comprise a fluorescent probe at the side chain of Lys15 and a ligand with affinity for a target molecule at the side chain of Lys8 or Lys34. Also disclosed are polypeptide scaffolds for use in biosensing applications with or without the polypeptide scaffold anchored to a solid surface.

Abstract: A method for site-selective acyl transfer in amidation of folded polypeptides and proteins based on the use of a chemical structure element comprising an imidazole function, such as histidine, in position i flanked by at least one functional group to be amidated, such as lysinc, in position i+3+4k where K is an integer equal to or higher than −1, or in position i−4−4n, wherein n is an integer equal to or higher than 0, and at least one activating group, such as serine, in position i+4+4n or i−3−4n, respectively.

Abstract: A catalytically active peptide comprising an imidazole function in position i flanked by at least one functional group to be amidated in position i+3+4k, where k is an integer equal to or higher than +1 or in position i−4−4n, wherein n is an integer equal to or higher than 0, characterized in that it also comprises at least one activating group in position i+4+4n or i−3−4n, respectively, wherein n is as above.

Abstract: The invention relates to a method of performing a chemical reaction between a reagent and a substrate, involving an acyl transfer mechanism, in the presence of an imidazole-based catalyst capable of forming a transition complex with the substrate. The catalytic imidazole function is provided by a chemical structure element comprising an optionally substituted imidazolyl group flanked on one or both sides by a group or groups capable of stabilizing the transition complex by molecular interaction with the acyl group. The invention also relates to such a designed chemical structure element, a method of producing it by recombinant DNA techniques and a vector therefor.